The U.S. Government has been interested in light, high performance cooled laser mirror assemblies for many years. The most recent generation has used single crystal silicon as the mirror face. Thermal expansion mismatch questions led to the use of single crystal silicon for the attached heat exchanger assembly as well thus eliminating any problem of residual stresses after bonding. Great strides in mirror technology were made in this effort but questions of system reliability remained. The present invention addresses this critical issue.